Compound can be prepared in two different ways: 1) By condensation of 8-chlorodibenzo[b,f]thiepin-10(11H)-one (I) with 2-dimethylaminoethyl chloride (II) by means of NaH in benzene - DMF at 60 C. 2) By condensation of 8-chloro-10-(2-chloroethoxy)dibenzo[b,f]thiepin (III) with dimethylamine.